20-Arpril-2009
SF
Big Idea
Negative numbers help us to model many real world situations.
Investigation 3: Subtracting Integers
Essential Question #3: How do I find the difference between integers?
Notes:None

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A1. Complte the addition sentence -17+13=?.
-17+13= -4


A2. Write a subtraction sentence that " Undoes " the addition sentence you found in pat 1.
4-(-13)=+17

B1. Complete the addition sentence -4+-18=?.
-4+(-8)= -22



B2. Write a subtraction sentence that " undoes " the addition sentence you found in part 1.
22-4= 18

C. Write a subtraction subtraction that solves each problem.
1. ?+-18=
6 ?=24 Subtraction Sentence: 24-6=18
2. ?+-13=-41 ?=-28 Subtuaraction Sentence: -28-(-41)=13
3. ?+6.1=-3.2 ?=-9.3 Subtraction Sentence: 3.2-9.3=-6.1
4. ?+negative one third= one third ?=two third Subtraction Sentence: one third + one third = two thirds

D. Write an addition sentence that solves each problem.
1. ?-(-6)=-6
?= 0 Addition Sentence: 0+(-6)=-6
2. ?-(-2)=3 ?=1 Addition Sentence: -1+3=2
3. ?-5.3=-7.1 ?=-1.8 Addition Sentence: 7.1+(-5.3)=1.8
4. ?- negative one fourth= negative three fourths ?=-1 Addition Sentence: -one fourths - negative three fourths = -1

Follow up

1. Can you write a different subtraction sentence to go with 3+11=14?
14-11=3.

2a. Complete the addition sentence 3.8+-2.6=?
3.8+-2.6=1.2

2b. Write a subtraction sentence.
3.8-1.2=2.6

3a. Complete the subtraction sentence -11-6=?.
-11-6=-17

3b. Write a addition sentence.
-17+6=-11

4. When you add positive and negative integers, sometimes you get a positive sum and sometimes you get a negative sum. Is this same true when you subtract positive and negative integers?
Yes, because it depends on the integers and their signs.
Eg. 11-5=6 & -8-(+3)=-11


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